1. Field of the Invention
This invention relates to pre-acting retractable extending fire sprinklers.
2. Background Information
Fire protection sprinklers may be operated individually, e.g. by a self-contained thermally sensitive element, or as part of a deluge system in which fire retardant fluid flows through a number of open sprinklers, essentially simultaneously. Fire retardant fluids may include natural water or appropriate mixtures of natural water and one or more additives to enhance fire-fighting properties of a fire protection system.
Fire protection sprinklers generally include a body with an outlet, an inlet connectable to a source of fire retardant fluid under pressure, and a deflector supported by the body in a position opposing the outlet for distribution of the fire retardant fluid over a predetermined area to be protected from fire. Individual fire protection sprinklers may be automatically or non-automatically operating. In the case of automatically operating fire protection sprinklers, the outlet is typically secured in the normally closed or sealed position by a cap. The cap is held in place by a thermally-sensitive element which is released when its temperature is elevated to within a prescribed range, e.g. by the heat from a fire. In some cases, sprinklers are not permanently positioned in their spraying position, but are installed above or behind a cover that conceals the sprinkler for aesthetic reasons, or to prevent the sprinkler from interfering with the function of the chamber such as in an anechoic chamber. In such cases, the sprinkler is retracted from its spraying position when not in use, and telescopes to its spraying position either automatically or as directed by a control system.
Telescoping pipes have been used in fire sprinkler systems. U.S. Pat. No. 5,160,174 to Thompson shows telescoping pipes and applications for such pipes in fire sprinkler systems.
U.S. Pat. Nos. 5,921,322 and 6,216,963 relate to a hydraulic device for regulating the speed of deployment of sprinkler heads in preactive sprinkler systems. These prior art sprinklers do not disclose a mechanism to retract the sprinkler head. In the prior art systems, a sprinkler head is installed at one end of an inner conduit. The inner conduit fits inside an outer conduit as a piston fits in a cylinder. There is an annular space between the inner and outer conduits. This annular space is bounded by slidable seals at each end. When a high-pressure fluid is applied to the inner conduit, the piston telescopes out of the outer conduit compressing the annular space between the cylinders. The prior art teaches that the fluid in the annular space is released either into the fire extinguishing media, to the outside of the outer conduit through a series of bleeder holes that can be varied in size to control the rate of travel of the piston.
Telescoping and retracting sprinkler systems have been used in irrigation systems. For example, U.S. Pat. No. 4,254,913 to Georgiev shows a retractable spray head for an irrigation system. U.S. Pat. No. 4,749,127 shows telescoping snow making apparatus that includes a telescoping and retracting spray head.
These applications do not show a retracting telescoping fire sprinkler.
A retractable telescoping sprinkler is disclosed. Some advantages of the retractable telescoping sprinkler include the ability to control the rate of deployment of a telescoping sprinkler, and its ability to retract to its undeployed position. The sprinkler can deploy and retract without draining fire-extinguishing media from the sprinkler head.
The sprinkler includes means for regulating the speed of deployment of the sprinkler head from the retracted position to the extended position and means for retracting the telescoped sprinkler head back to a retracted position.
The sprinkler may be mounted in any orientation convenient to the installation. The sprinkler may deploy vertically coming down from a recess in a ceiling, horizontally projecting from a wall, or at any angle from an oblique surface as required by the details of the installation. Any sprinkler head providing a desired distribution pattern and coverage may be used.
In one illustrative embodiment, the sprinkler includes an outer conduit and an inner conduit. The two conduits are sized such that the inner conduit can slide into the outer conduit and define a space between the conduits. If both conduits are round tubes, as may be convenient, the space will be annular. However, the conduits are not limited to round tubes, but can be any shape that has adequate strength, heat tolerance, and flow capacity to meet the requirements of the installation. The conduits have stops at their ends that limit the motion of the inner conduit such that the inner conduit will not slide out from the outer conduit when the inner conduit extends. Bearings may be positioned to guide or support the inner conduit as it extends and retracts in operation.
Fluid seals are positioned between the inner conduit and the outer conduit. These seals slidably engage the walls of the conduit so that they longitudinally compress the annular space between the conduits when the telescoping sprinkler extends. Additionally, when the telescoping sprinkler retracts, the seals longitudinally extend the annular space between the conduits.
A flow control valve can be connected to an outlet from the annular space near the point where the inner conduit extends from the outer conduit. When the sprinkler extends, the space between the conduits is compressed longitudinally, the valve allows fluid to flow from the space at a predetermined rate. The rate can be varied as desired to allow for faster or slower deployment, or for operation with different size conduits. The fluid can be any suitable fluid, either gaseous or liquid. The fluid may be a mixture of two or more liquids to obtain a desired flow profile.
The flow control valve is also fluidly connected to a reservoir or expansion tank. When fluid is pressed out of the space between the conduits, the fluid flows into the reservoir. When the sprinkler retracts, the fluid flows from the reservoir to through the flow control valve into the space between the conduits. Optionally, pressure may be applied to the reservoir to assist in retracting the sprinkler.
One or more springs may be mechanically connected to the outer conduit and the distal end of the inner conduit. The springs maintain tension holding the telescoping sprinkler in the retracted position until the sprinkler is deployed. When the sprinkler is deployed, fire-extinguishing agent is supplied under pressure to the conduits. The pressure of the fire-extinguishing agent applies a force to extend the telescoping sprinkler. This pressure pushes the inner conduit to the extended position. This extension compresses the space between the conduits and forces fluid through the flow control valve into the reservoir. Additionally, the springs are extended under tension.
When the pressure of the fire-extinguishing agent is removed, the springs retract. The inner conduit slides back into the nested position within the outer conduit. The sealing means slide along the walls of the conduits expanding the volume of the space between the conduits. Fluid flows from the reservoir through the control valve back into the space between the conduits. This fluid return may be assisted by application of pressure to the reservoirs containing the fluid.